MARINE MOLLUSCA OP THE UNITED STATES. 151 



opalescent, with a purple or bluish iridescence often in the form 

 of rays. 



Length It, height 10 mill. 



New York. 



Genus STEIGILLA, Turton. 

 Brit. Bivalves, 117. 1822. 



This genus is readily recognized by its obliquely-sculptured 

 valves and its orbicular shape. 



1. S. CARNARIA, Linnaeus. Figs. 362, 363. 



(Tellina.) Syst. Nat., edit. xii. 1119. 1767. 



Suborbicular, convex, strong, glossy, pink or rose color ; inside 

 rosy ; lateral teeth distinct and nearly equidistant. 



Southern Coast to W. Indies. 



2. S. FLEXUOSA, Say. Figs. 364, 365. 



(Tellina.) Journ. Philad. Acad., ii. 303. 1822. 

 Strigilla mirabilis, Phil. Wiegm. Archiv., 260. 1841. 



Shell suborbicular, white, smaller and more convex than S. 

 carnaria, the flexuous lines more numerously angled. 

 Length 12, height 11 mill. 



North Carolina to W. Indies. 



Doubtful Species. 



3. S. MERA, Say. Fig. 366. 



(Tellina.) Am. Conch., vii. t. 64, f. 2. 



Shell ovate-orbicular, concentrically striated, hinge bidentate, 

 with a lateral tooth in one valve. 



South Carolina. 



The above description and figure refer to a species which has 

 not been identified ; its analogies of form would seem to indicate 

 its position in this genus. Mr. Say remarks that " in a particular 

 light it has a slight appearance of longitudinal lines." It is 

 quite possible that it is a worn specimen of Strigilla in which the 

 zigzag oblique lines are obsolete. 



Genus MACOMA, Leach. 

 Journ. de Phys., Ixxxviii. 465. 1819. 



1. M. BALTHICA, Linnaeus. Fig. 36t. 



(Tellina.) Syst. Nat., edit. xii. 1120. 1767. 

 Psammobia fusca, Say, Journ. Philad. Acad., v. 220. 1827. 



Shell thin and fragile, ovate orbicular , beaks small, almost 

 central. Surface with concentric wrinkles; rounded before and 



